84 BOTANICAL GAZETTE funy 
MacKeEnzig,’ in continuation of his studies of Carex, has presented the 
“Californian representatives of the Ovates.” The list includes 25 species, 
15 of which are described as new. 
' Rosrnson® has published a detailed monograph of the American genus 
Brickellia. The need of it, the author remarks, ‘‘ presents no unusual condition 
among the larger genera of the Compositae.” The gi species, 11 of which are 
new, are grouped in 9 sections. The systematic presentation is preceded by a 
full discussion of the diagnostic value of the characters used. 
RYDBERG,’ in continuation of his studies of the Rosaceae, has investigated 
the species of Rosa occurring in — and Nevada. He recognizes 34 
species, 12 of which are described as 
Tipestrom™ has described a new tie (A. platyphyllum) from the 
Wallowa National Forest of Oregon.—J. M. C. 
Effect of carbon dioxide on respiration—Kipp" has studied the effect of 
various concentrations of carbon dioxide on the rate of anaerobic and aerobic 
respiration of seeds of peas with testas both intact and removed. The work 
is marked by brilliancy of design, and in the main of aepigaroae In concen- 
trations of CO, ranging from o to 50 per cent, the d anaerobic 
respiration is proportional to the square root of the concentration. As the 
concentration rises above 50 per cent, the depressing effect falls more and more 
behind the square root of the concentration. Carbon dioxide also depresses 
aerobic respiration when measured either by oxygen consumption or CO, 
production. In the latter case the concentration effect is similar to that in 
anaerobic ew soidgina is deficient, CO, has no depressing effect . 
as ; 
atio 
occurring in n starving tissue) i is thus depressed The work throws considerable 
" Inwotk ofthis sft ee bold be aretha the lt sterile and that 
ca om Ce ction is that of the s EERE | <r . : ae 
3 7 MacKexat, K. K., Notes on Carex. XI. Bull. Torr. Bot. Club 43:601-620. 
=: cance 
*R s, B. L., A monog ph o f th g Brickellia Memoirs Gray Herb. i. 
ny PP. 151. Sigs. 95- 1917. a 
° Rypsere, | 
DEST. ms - wae, Alm tpn, 9. nv ‘Torreya 162242. 1916. 
, The influence of c | dioxide. Part II. 
Pex Axet, Noteson Rosaceae, ae Bull. Tor. Bot. Club 44:65-84 oS 
